


You Can Never Go Home Again

by st_aurafina



Series: Sirius as Companion [1]
Category: Doctor Who (2005), Harry Potter - J. K. Rowling
Genre: Crossover, Gen
Language: English
Status: Completed
Published: 2011-01-10
Updated: 2011-01-10
Packaged: 2017-10-14 15:24:40
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,830
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/150720
Author URL: https://archiveofourown.org/users/st_aurafina/pseuds/st_aurafina
Summary: <blockquote class="userstuff">
              <p>On the other side of the Veil, Sirius can't help his friends, but he can help someone else's.</p>
            </blockquote>





	You Can Never Go Home Again

**Author's Note:**

> Written for cherryfeather for the dw_cross exchange, 2008.

It took a long, long time to fall through the veil, long enough for Sirius to observe with a strange, detached interest the way that Bellatrix's curse spread inch by inch across his chest, and how his heart thumped hard against his ribs in rebellion. There was cold that crept into his bones, and swirling lights behind his eyelids, and energy that skittered along his nerves, exiting from fingertips and toes. Then there was impact that forced his last breath out with a gasp, and blissfully soon after that there was nothing.

When he woke, Sirius was lying prone on a metal-grilled surface in an eerily lit room. His muscles ached like he'd been wrestling with a bear; every breath creaked and groaned. The heaviness in his chest was not helped by the man sitting astride him, listening to Sirius' heart through his robes with a Muggle stethoscope. The man tilted his head, and moved the disc from one side of Sirius' chest to the other. "Well, you're human, whoever you are." The man folded the stethoscope up with a snap, and it vanished into a suit pocket. While he was distracted, Sirius took the opportunity to shove the strange man hard in the ribs. Once the man was down, Sirius scrambled to his feet, and took cover behind a large pillar in the centre of the small room. He eyed the blinking lights and instruments suspiciously. This was a Muggle place, if ever he'd seen one.

The man that Sirius had knocked down rolled nimbly to his feet. "And you're awake! You're all so resilient, aren't you? Take a tumble through the Vortex, completely unprotected, and five minutes later you're ready to rumble. Or, at least you are until the chronal vertigo sets in." He pulled out a pocket watch, and flipped it open. "Which should be hitting in three, two, one…"

Sirius' knees folded and he fell, head swimming. He spread his arms and legs out like a starfish, as the floor spun around beneath him, until he felt he was looking down from a great distance, plastered to the floor which had become the ceiling. When he finally threw up, the vomit didn't plummet to the ground as it should, but spilled over his front. He choked in outrage, and tried to raise his head, but space still swooped around him. The man, improbably walking upside down on the reversed floor, crouched down beside him and patted his shoulder soothingly.

"Oh, that's very rock-star, isn't it? Never mind, the Doctor's here."

***

The first thing that Sirius demanded – once he could stand upright, and the purpose of the Doctor's time-vessel had been explained – was to be taken back to the battle from which the Veil had snatched him. The Doctor agreed.

"Can't have a point of entry to the space/time continuum sitting unguarded in twentieth century London," he said, tapping a series of numbers onto a keyboard. He looked at Sirius, who was gingerly peeling himself out of his soiled shirt. "You might want to get a change of clothing – there's probably something in your size upstairs."

When Sirius came down the spiral staircase, fidgeting with the elaborate lace cuffs on the shirt he had borrowed, the Doctor was leaning against the rail surrounding the console, with a puzzled expression.

"I can't get the old girl anywhere near that point in the Vortex – it's swimming with transient tachyon displacement energy, which, I admit, is odd. It should dissipate, though, given time. " His voice tailed off as he walked around Sirius, tugging at the seams of the velvet smoking jacket. "This is familiar…"

Sirius dashed the hand away with an irritated gesture. "Enough! So much time has passed already – if you can't take me back to the Ministry, then anywhere in London will do. I can make my own way back."

The Doctor shrugged a shoulder. "Time is all so relative, you know. We just need to wait a few hours – in your personal time stream, that is – then when the displacement energy has settled down, I can have the TARDIS drop you off at the very moment that you left."

Sirius thought of Remus and the children, frozen in time, and fixed the image in his mind. He took a deep breath, and let his shoulders relax. They would be safe until the Doctor could return him there.

The Doctor frowned. "I'm sorry – which Ministry is this, exactly?"

Sirius pressed his lips together, desperately trying to recall the Muggle nomenclature. He remembered a recent Tube strike, and some choice words Remus had muttered over the morning papers. "Transport. The Ministry for Transport."

"You were in a battle for your life, in the Ministry for Transport?" The Doctor was nonplussed. "In nine hundred years, I have never yet been able to fathom British bureaucracy."

***

They sat on the terrace of a little enzyme-café on a world that the Doctor liked because the sky was lavender, and how often do you see that these days?

"What's that name you keep calling me?" he said, poking at his pre-digested slurry with his straw, "Mupple? Miggle? Is that some kind of slang that I've missed out on? I swear, once the internet arrives, your languages start evolving faster than even I can keep up with."

Sirius sipped his tea, glad he'd taken the time to explain herbal infusion to the waiter. Potions class was good for something after all. "Muggle. It's what we call people who aren't like us."

"What, you mean, alien?" The Doctor waved his hand at the purpling sky.

"No. Well, you're the first alien I've met, but you're a still a Muggle." Sirius picked up a starchy twig from the side of his saucer. "Is this a biscuit?" His stomach was growling.

"S'garnish." The Doctor's cheeks were hollowed with the effort of drawing his glutinous shake up the straw, and he swallowed with difficulty. "Not really edible, not with your metabolism." He flagged down a waiter who leaned over their table with willowy eyebrows raised in query. "I'm sorry, this is terribly underdone – would you mind?" He looked up at the sky politely as the waiter extruded more digestive essence into the narrow tumbler. Sirius took the chance to slip out his wand and transfigure the twiggy garnish into a macaroon, then he popped it into his mouth with a satisfying crunch.

"I saw that!" The Doctor pointed an accusatory finger at Sirius, then used it to dab up some crumbs from the table top. He touched his finger to the tip of his tongue, and his eyebrows shot into his hair. The waiter, startled, scurried away as fast as its pseudopodia could carry it. "Coconut! There isn't a coconut in this galaxy. You'd have to travel ninety-seven million light years just to reach the closest thing to a palm tree, and even then, they're a carnivorous race." He stood up, and pressed both his palms on the table menacingly. "Where did you get that macaroon, Sirius Black?"

***

"There's no such thing as magic. It's physics. You're performing molecular level conversion, somehow. With a wooden stick." Back in the TARDIS, the Doctor balanced Sirius' wand on one finger, " _Corylus avellana_ , if I'm not mistaken. Hazel. Did you know the druids would eat hazelnuts before they engaged in divinatory rites? Something to think about next time you bite into a piece of nougat."

Sirius leaned a hip against the console and crossed his arms. "I'm not arguing with you. There's no such thing as magic. It's all molecular… stuff."

"You're not very convincing." The Doctor threw the wand end over end at Sirius, who caught it and tucked it under his arm. "I think the most likely explanation is that you belong to a cult of advanced physicists who are convinced that they're doing magic." He drew his sonic screwdriver out and pointed it at the ceiling. "LO, I SUMMON THE DARKNESS!" He pressed the button, the end glowed blue, and the lights in the console room went out. "See? I'm a wizard, too."

" _Lumos_ ," Sirius held his wand aloft and cool light spilled across the room. "You have an electric wand? Andromeda was right – electricity is really just Muggle penis envy."

There was an uncomfortable silence. The Doctor switched the lights on again, and idly flipped a few switches on the console. Sirius began to regret his hasty words. He tucked his wand away and held out his hands in a placating gesture. "I'm sorry; that was incredibly ungrateful. You've been very gracious, and I appreciate your help. I'm just worried about my friends."

The Doctor's face brightened. "Of course you are! Let's try that re-entry plan again, shall we? Or better still," he ducked under the console, pried open a panel, and slithered halfway inside, "We could build a filter, something to work around that tachyon displacement." He hooked a foot around Sirius' ankle and dragged him closer. "Keep an eye on that scope, there."

"What's a scope?" Sirius looked down at the console in front of him. There were more switches than on Arthur Weasley's desk, and very few of them were labelled.

The Doctor's voice drifted up through the gaps in the panelling. "The telly-screen-thing. There's a green line – tell me if it starts to break up."

Sirius watched the green line for a while, but it didn't seem to be changing, despite the alarming sounds coming from beneath the console. There was a brilliant flash of blue light, and the Doctor gave a mighty yelp.

"Are you all right?" Sirius bent down to peer under the console; the Doctor was blowing on the blackened ends of his fingers.

"Any change in the scope?"

Sirius straightened up and peered at the screen – the line continued unbroken. "No change. But something is chirping. " He tracked the sound down to another instrument panel, and read the display. "It's coming from a little silver box that says 'Chiswick'."

"What?" The voice was incredulous.

Sirius spoke louder and more clearly. "It says 'Chiswick'!"

"I heard you the first time." The Doctor scooted out from under the console and snatched the instrument from the panel, holding it to his ear. "Hello?" His voice was oddly tentative. "Wilf? How did you get this number? Is everything all right?" He turned away from Sirius, walking all the way to the far wall, leaning against with the phone tucked into the crook of his shoulder. "Slow down, Wilf. No, you're right, that shouldn't be happening."

***

Chiswick was Muggle territory: neat rows of identical houses crammed close together, divided by low fences and fussy little over-tended gardens. They'd left the TARDIS at the rear of a fish and chip shop. "Don't want to trigger any more memories by parking outside," the Doctor muttered to himself as he locked the door and tucked the key the away.

Sirius walked beside the Doctor as he strode swiftly along the uneven pavement and up the narrow pathway of one of the indistinguishable houses. The buzzer made a tinny, hollow noise from inside, and the door was opened by a woman with ash-blonde hair in a neat bob. Her lips tightened at the sight of the men at the door. "Doctor."

"Sylvia." The unease between the two was tangible.

"You'd better come through, then." She led them to the living room, and cleared a muddle of wires from the sofa, gesturing towards an electric kettle, lying partially disassembled on the broad wooden dining table. "Forgive me if I don't offer you tea. I'm going to check on my daughter."

The Doctor leaned over the table, rubbing a hand across his chin as he picked at the remains of the kettle. Sirius looked around the room – there were pieces of electrical appliances strewn across the mantelpiece and the floor, some deliberately arranged in complex patterns, others lying in shattered pieces where they had been flung at the wall. The scratches and gouges in the smooth cream paint made Sirius' skin crawl; he knew the patterns made by someone fighting to free themselves from a prison cell.

"Doctor, what happened here?" There was a faint smell of ozone in the air. It reminded Sirius of the classroom after a long and tiring lesson in transfiguration.

The Doctor stood up straight, holding the shell of the kettle. "I did." He turned the kettle around and around in his hands. "Donna Noble was my friend. She was hurt because of me, and I had to wipe her mind to save her life. Now it looks like I didn't even do that properly, because she's trying to make something that she can't possibly remember. She's trying to build a TARDIS out of kitchen junk." He laughed weakly. "It's not bad, either."

Sirius took the kettle from him, and drew his wand. " _Reparo!_ " The elements and wires snaked off the table and slotted neatly into the base of the plastic urn. He handed it back to the Doctor. "Is there anything I can do to help?"

***

The Doctor took tea up to Donna's family, then padded down the stairs with the tea-tray tucked under his arm.

"She's stable for moment, sleeping. Wilf says she's doing all this in her sleep, doesn't know anything about it in the morning." At the bottom of the staircase, Sirius passed him a full mug of tea, and he sat on the last step with his knees drawn up, nursing it between his palms. "I had to do it, you know." The Doctor spoke without looking up. "All that knowledge contained in a human mind, it would have killed her. It might yet."

"I doubt it's the kind of thing you would do light-heartedly." Sirius leaned against the banister.

"What would you wand-wielding types do?" The Doctor waved a hand. "Assuming that we're talking about advanced physics here, and acknowledging that there is, in fact, no such thing as magic. Hypothetically speaking."

"With an incomplete Obliviation? It's a complicated spell to begin with; when it goes wrong all sorts of unpredictable things can happen. Memory fragments can recrystallise, especially if she feels the absence of them." Sirius sipped at his tea, thinking of those scratches on the wall. "She relished the freedom of travelling, I imagine? Perhaps she's looking for a way to travel again."

"That's human minds for you – too interconnected for your own good, thoughts going all over the place." The Doctor looked glumly into his tea. "Something must have slipped past."

"It must have been a tenacious thought, something she valued highly," said Sirius. "The sort that people bottle, and look over again and again. They're easy enough to extract – you'd need a Pensieve, of course. And someone with a knack for memory charms, which isn't me, I'm afraid."

The Doctor looked at him thoughtfully. "I'll bet you know someone who is, though."

***

"This had better not be one of those reality TV things." Donna Noble was a tall, red-haired woman, and she was definitely not impressed to be blindfolded, driven down the street and handed over to two complete strangers. "Unless it's that Ground Force lot; the back yard could use a makeover." She slammed the door of the hatchback and sniffed deeply. "Are we at the chippie? There's a hypnotherapist working at the chippie?"

Her grandfather put his hand on her arm. "Donna, sweetheart, I give you my word you're in good hands. It's just their way." He leaned in close to whisper surreptitiously in her ear. "You know these alternative medicine types – eccentrics, the lot of them, but their hearts are in the right place, and you never know. It might help with that insomnia you say you don't have."

"Hypnotherapy." Donna gave a snort. "At the chippie. All right, do your worst, Svengali!" She held both her hands out into open air. The Doctor slipped his hands into hers, and walked them both backwards through the door of the TARDIS. Sirius gave Wilf a nod, then pulled the doors closed behind them.

***

"I know this whole hypnotherapy thing is a con," Donna kicked out a leg – from her seat she could almost brush the central plinth of the console. "I don't know what my mother has been telling you, but I didn't do any of it. And what's this blindfold for, if you're not robbing me or something?" She swung her foot back, nearly tripping the Doctor as he hopped over her leg with an armful of long, loopy cables.

Sirius stood on the other side of the row of seats with his arms crossed. "Why is she blindfolded?"

"And why are you whispering?" Donna tilted her head towards them. "You may as well be upfront; I'm not going to be brainwashed by your cult. Go on, take that as a challenge." She pushed the blindfold up a little, feeling in front of her with one hand.

The Doctor sighed, and tugged the blindfold back down. He spoke low, with a slight Northern burr. "You're blindfolded to enhance the," he waved his hands vaguely, "The alpha induction state. Makes it easier to hypnotise you. Why don't you tell me about your insomnia?"

Donna slumped back in the seat. "Oh, I don't have insomnia. My mum doesn't know what to do with herself if she doesn't have someone to worry about. You should hear the fuss she makes over this macrobiotic diet she's trying get us all on."

While Donna spoke, the Doctor tugged Sirius closer. He pressed his mouth against Sirius' ear and whispered very softly, "She's blindfolded to prevent triggering memories. And I'm whispering because she might recognise my voice. And I need you to wear these electrodes." The Doctor thrust a handful of wires into Sirius' face.

"What?" Sirius recoiled in alarm, but the Doctor had him in a firm grip.

"Telepathic navigation – you said this place, this Hogwarts, is hidden or shielded. All you have to do is think of the location, and the TARDIS will find the way." He pressed adhesive discs to Sirius' temples.

Sirius shook his head. "It won't work - you can't Apparate in or out of Hogwarts."

The Doctor grinned. "Laws of Magic! Physics! You lot love to build these systems, and then you let them box you in. Concentrate on the smell, the sounds, the very essence of the place. You can do it." He gave Sirius a clap on the back. "Now, get to work!"

Sirius closed his eyes, and thought about Hogwarts: the corridors and classrooms, the secret places that he sought out with his friends. Beneath his feet the steel grille quivered and he knew without looking that the central rotor was in smooth, silent motion. With a deep breath, he remembered the way the sun slanted through the windows in the uppermost room of Gryffindor Tower, warming the grey stones, casting long shadows against the bodies of his friends. His stomach clenched, thinking of Remus trapped in time at the Ministry, waiting for Sirius to reappear through the Veil. The floor bucked, and a grinding complaint came from the console.

"Oh, no, no, no!" Sirius could hear the Doctor frantically flipping switched. "You're changing course!" He gave Sirius' body a shake. "I told you, the TARDIS can't go there! If you force her, she'll shake apart!"

"I said it wouldn't work!" Sirius tried to recapture the memory of late afternoon in the Tower, but all he could think about were the cold marble floors of the Ministry of Magic. The TARDIS groaned; a terrible noise.

The room lurched and Donna shrieked, wrapping her arms around the back of the chair. She tore off the blindfold, stared around in confused recognition, then took two strides to the console and slapped Sirius hard across the face. "I don't know what the hell is going on but you'd better buckle down and concentrate. I don't want to die."

Sirius closed his eyes again, and took slow, deep breaths. He fanned out his fingers, imagining sun-warmed stone under his fingers. "Let me go back there, please take me back." He was so immersed in the memory that he didn't hear the central rotor begin to move, or the faint exhalation as Donna collapsed to the floor.

***

Sirius had no doubt that when the TARDIS door opened, they would see the room at the top of Gryffindor Tower. He did not expect that Professor Dumbledore would be there waiting for them. Dumbledore peered at Sirius over the top of his spectacles for a moment, then walked to the stairway, and locked the door. "Mr Black, how very unexpected to see you at this time!" Professor Dumbledore walked back to the TARDIS with his hand outstretched. "And you've bought guests, too."

"Forgive me, Headmaster, but the situation is urgent." Sirius leaned closer and whispered a question."How is everyone at the Ministry? Is Harry safe?"

"I really couldn't say, Sirius, but I'm certain it will all work out for the best. My immediate concerns are for your friend who is indisposed."

The Doctor carried Donna out of the TARDIS, his face sombre. "Sirius, we have to do this now. Her mind is burning up." He lay her down on the stone floor, and crouched beside her.

Dumbledore rested his hand against Donna's forehead. "Oh, dear."

"I thought, perhaps, you could help her." Sirius found himself irritatingly and inexplicably tongue-tied in front of his former Headmaster. "I know you have a Pensieve."

"Of course." With a gesture, the stone font appeared before them. "I'll need your assistance to help me separate the merged consciousness, Mr...?"

"Doctor," said the Doctor. "And of course." The two of them bent over the unconscious woman, and Sirius watched as Dumbledore began to spool silvery thoughts from Donna's mind into the Pensieve.

It took a long time: the Doctor peering into the Pensieve, sorting Timelord memories from human, while Dumbledore moved memories back and forth from Donna's mind. Sirius paced nervously up and down the room, looking out of the windows. There was a sudden clatter on the stairway and Dumbledore looked sharply at the door. "Do not allow anyone entry into this room, Mr Black, no matter what you hear at the door."

Sirius moved to press his body against the door, but froze as he heard words drifting up from the floor below.

"I'm telling the truth, Prongs! She said she'd rather kiss the undead mouth of a rotten Mummy corpse before she'd lay her lips on yours. Those were her exact words."

"You're just jealous, Pads."

"No need to be jealous when I'm getting all the tongue action a man can dream of."

"I don't think pashing Moony in the cupboard really counts as the same thing."

Sirius' head pounded as blood drained to his feet. That was him climbing the stairs, but the him of 1965, fighting with James about Lily Evans. Remus was probably just behind them, his nose buried in a book, and that bastard, that treacherous bastard, was most likely huffing and puffing his way up from the Common Room. If Sirius opened the door, if he took those twelve stone steps, he could dispatch Wormtail and stop any of the horrible events of the future from happening. Sirius felt the latch on the door turn, and found that his hand it was on the handle. The door was locked. He reached for his wand. The footsteps were almost to the top of the stairs.

"Sirius Black! You will stop what you are doing right now." Dumbledore's voice boomed all around him, and on the other side of the door, the footsteps stopped. There was a furtive, frantic whispering then the footsteps reversed, pelting down the steps and fading away.

Sirius turned to look at Dumbledore, who was once again drawing memories from Donna's mind. "I remember that day. We never knew why you were in this room. We thought that we'd all be called up to your study and punished." He shook his head. "I remember – it happened just like this."

The Doctor laughed softly to himself as he bent over the Pensieve. "That's because it's happening right now."

"And that is why you must not interfere. This is your past, Sirius Black." Dumbledore's face was composed. "It would change the person that you have become."

"I don't see how that could be bad." Sirius knelt down by Donna's feet. "Don't you want to know what happens? To help our friends, to give us an advantage?"

Dumbledore smiled beatifically. "My dear boy, our friends would not be our friends if we were the kind of people who relied on dishonesty to triumph. They will do the best they can, as we will do here."

***

They sat on the same terrace, though the lavender sky was now heavy with umber clouds.

Donna had been adamant that they return her to Chiswick. "I want some space to think my own thoughts for a while," she said, knocking on the side of her head. "It feels like someone gate-crashed a party in here."

The Doctor had seemed uncertain. "Are you sure? Don't want to go for one last spin?"

Donna shook her head. "Home, James. I need some air." She gave the Doctor a slap on the arm. "And don't give me that fretful face, you've got Mr Velvet Trousers to keep you company."

Now, at the café, the Doctor poked miserably at his protein shake and tried to make small talk. "I have a terrible soft spot for skies that aren't blue. It's a hang-over from my childhood."

Sirius crossed his arms. "You've been evasive since we left Chiswick. Are you going to take me back to the Ministry?"

"Yes, well. About that. It's that tachyon displacement, you see." The Doctor looked up hopefully, as if this would provide explanation enough, but Sirius' expression was blank. "The reason the TARDIS couldn't materialise where you slipped into the Vortex is because there are safety protocols that prevent me from causing a paradox."

"I don't understand." Sirius clenched his fists. At the edge of his vision he could see the waiters hovering nervously. He lowered his voice and leaned closer to the Doctor. "Just tell me what you mean. In the simplest terms possible. I have to go back."

The Doctor pushed his protein shake away. "When you fell into the Vortex, you should have died. You didn't die, because I happened to be travelling through that part of time and space. But you should be dead. Your personal timeline is broken – you can't ever go back to that date again, not without causing terrible damage to the fabric of space and time."

"I thought I was dying." Sirius remember the impact of Bellatrix's curse against his chest. It was odd how the clouds kept gusting across the sky. He watched a bead of moisture crawl down the glass tumbler on the table. "Everyone thinks I'm dead?"

"In their timeline you are dead, and your death influences their decisions and actions; if you were to return, they would make different choices, history would unfold in a new shape. And the effect would be huge – you must be a person of some significance given all the coincidences that flock around you. I just happen to be moving through the exact part of the Vortex that will allow you to move inside the walls of the TARDIS; you just happen to be the one person who can help Donna Noble – there's forces acting here that I can't explain, but I'm not going to argue with. You, Sirius Black, are a person of destiny."

Sirius pulled the protein shake over towards him, yanked the straw from the tumbler and threw it on the ground, despite the shocked rustling from the nearby waiter. He took a mighty gulp from the glass and promptly gagged. "That's just horrible."

The Doctor nodded. "I know. But it's worth it for the view."

"I don't want to be a person of destiny." Sirius pushed the tumbler away from him. "I want to help my friends."

"Destiny's flighty like that." The Doctor pulled the tumbler back towards him and took a sip. "And your headmaster seemed to have faith that your friends will win out."

Sirius watched the clouds swirling above them, and remembered that moment of suspension when he had tumbled through the Veil; how he had thought it his last moment, and how it had lasted forever. He thought he was dead then, how strange to think he was alive now. His stomach churned with fading adrenaline and he was suddenly, prosaically, hungry. "Do you know any places where the food isn't pre-digested?"

The Doctor gave a ravenous grin. "I know places where it's so undigested you have to hunt it down first. Shall we go?" He pushed away from the table and stood up.

Sirius nodded. As the two of them walked towards the TARDIS, he wondered if the Doctor was a dog-person.


End file.
